The present invention relates to the field of image processing. More particularly, the invention relates to a method for processing camera shot films and for generating therefrom improved computer games which include variable speed, selected by the player.
Computer games are widespread nowadays. They typically employ animation or Computer Generated Images (CGI) techniques, in which images are generated according to algorithms that are relatively simple to formulate, with respect to their mathematical aspects. This relative simplicity, enables CGI based computer games to have high level of interaction. On the other hand, CGI graphic quality is substantially degraded concerning the experience felt by the player, comparing to video graphic quality.
Although video stream graphic techniques have superior quality, they lack interaction. Their graphic representation must track the video camera path, each time the game is played, turning the game into a non-attractive one. In addition, the mathematical representation of a video stream is very complicated and thus, practical almost impossible.
The technology employed in the art for video image processing suffers from several drawbacks, the most important of which being: 1) that there is only a limited feeling of reality, since scenes are pre-determined, constrained to the path, plot and events that were shot and recorded by the video camera; 2) data rates required for display of video streams are very high (in a typical .beta. video stream, 25 frames are displayed at each second, each frame is represented by 0.8 Mbyte, resulting in data rate of 20 Mbyte/Sec); 3) those scenes that appear near an interactive event give the feeling of discontinuity; 4) the range of intermediate speed values is limited. Thus, there are speed values that can not be reached using prior art methods; and 5) more importantly, interactive processing of video streams can not be carried out by conventional Personal Computers (PCs), to give satisfactory results.
Interaction of games may be improved substantially by manipulating the speed of video streams related to the game. One known method is based on changes in the frame display rate of the stream, by dropping frames from the original sequence (usually used for acceleration) or by inserting new frames which may be duplicates of some original frames. This method is widely used for converting video films from PAL (European standard for color TV) to NTSC (American standard for color TV) format, and vice versa. However, since the human eye is sensitive to irregular motion, poor results were achieved using this method concerning the feeling of continuity. In addition, speed values are pre-determined and can not be changed in real time.
U.S. Pat. No. 4,668,986 to Furukawa discloses a method for motion-adaptive interpolation of video signals. A number of motion vectors are computed for each moving object, generating a new representative motion vector.
U.S. Pat. No. 5,557,684 to Wang et. al describes a system for compressing image data for transmission by encoding the data into multiple layers. The system stores images as a series of layers determining the boundaries of regions of coherent motion over the frame, together with associated motion parameters. These motion parameters are coefficients of motion equations that describe the transformations between successive frames by formulating a motion model for each region within a frame. Each image is segmented into regions of coherent motion and defines associated layers of intensity, motion parameters, and depth.
U.S. Pat. No. 5,565,920 to Jungwoo et al. describes a method for video data compression using adaptive motion interpolation. Temporal segmentation is used to dynamically adapt motion interpolation structures for video compression.
Notwithstanding the very high commercial importance of sophisticated computer games, and the many efforts put into the manufacturing of games in the computer industry, the art has so far not successfully addressed the severe problem of producing interactive computer video games, based on real life images. It is an object of the invention to provide a method for manufacturing interactive computer games of improved quality, using real life shots.
It is an object of the invention to provide such interactive games in which the speed of displayed video streams is manipulated interactively to run slower and faster.
It is an object of the present invention to provide a method for real time computation and generation of virtual frames displayed as image sequences, which overcomes the drawbacks of the prior art.
It is another purpose of the invention to provide computer games utilizing pre-shot image sequences, which permit to effect smooth speed changes without the need for large databases of pre-stored images.
It is another object of the present invention to provide a method for carrying out and for storing most of the required intensive processing, in advance, while the display of any desired speed is carried out, in real time, using a fast, simple computation.
Other purposes and advantages of the invention will appear as the description proceeds.